[xep-support] Change-bar behavior

Gentlepeople,

When XEP 4.2 was released, support for change-bars was included by
implementing the emerging XSL FO 1.1's definitions, but placing the two new
elements into the RenderX extension namespace (the "rx:" namespace).

My first experiments with this exciting new facility revealed that I would
get a validation error if I used the elements in any place other than
places where %block;, %inline;, or CDATA could appear --- for example,
surrounding a <fo:list-item/> element with change-bar elements was a
validation error. I submitted a comment to the XSL FO development task
force in the W3C and they agreed that their intent was to allow these two
elements virtually anywhere in an FO document, including surrounding
<fo:list-item/>.

One of the wonderful people at RenderX, Sergey Groznyh, responded to me
saying "In RenderX implementaion, the "validation" phase prevents further
out-of-context change bar processing. It is already possible to process
them anyway when validation is turned off (by setting the appropriate
configuration option to XEP). So the proposed changes will require only
minor modifications to the validation stylesheet."

However, when I tried this out by manually inserting <rx:change-bar-begin
change-bar-class="a" change-bar-style="solid"/> immediately preceding
<fo:list-item...> and <rx:change-bar-end change-bar-class="a"/> immediately
following </fo:list-item>, there is no change-bar inserted into my PDF
document. But, if I manually insert those same elements within a
<fo:block>...</fo:block> or surrounding a <fo:block>...</fo:block>, the
change bars appear as desired.

Here's an FO fragment that does work:

<rx:change-bar-begin change-bar-class="CB" change-bar-color="red"
change-bar-placement="outside" change-bar-style="solid"/>
<fo:block>[Schemata] ISO/IEC 9075-11:2003, <fo:inline
font-style="italic">Information technology languages SQL Part 11:
Information and Definition Schemas SQL/Schemata)</fo:inline>. </fo:block>
<rx:change-bar-end change-bar-class="CB"/>

And here is one that does NOT:

<rx:change-bar-begin change-bar-class="CB" change-bar-color="red"
change-bar-placement="outside" change-bar-style="solid"/>
<fo:list-item space-before.optimum="8pt" relative-align="baseline"
hyphenate="true"><fo:list-item-label end-indent="label-end()"><fo:block
text-align="start"/></fo:list-item-label><fo:list-item-body
start-indent="body-start()"><fo:block>[Schemata] ISO/IEC 9075-11:2003,
<fo:inline font-style="italic">Information technology languages SQL Part
11: Information and Definition Schemas SQL/Schemata)</fo:inline>.
</fo:block></fo:list-item-body></fo:list-item>
<rx:change-bar-end change-bar-class="CB"/>

I suspect that Sergey may have been incorrect when he said that XEP already
processes these elements if validation is turned off.

Could somebody from RenderX clarify this situation and, if I'm doing
something wrong, tell me how to correct it. If XEP 4.2 does not, in fact,
support the change-bar-begin/-end elements "everywhere", is there some
guess about when a version that does support that capability might show up?

Thanks!
    Jim

========================================================================
Jim Melton --- Editor of ISO/IEC 9075-* (SQL) Phone: +1.801.942.0144
   Co-Chair, W3C XML Query WG; F&O (etc.) editor Fax : +1.801.942.3345
Oracle Corporation Oracle Email: jim dot melton at oracle dot com
1930 Viscounti Drive Standards email: jim dot melton at acm dot org
Sandy, UT 84093-1063 USA Personal email: jim at melton dot name
========================================================================
= Facts are facts. But any opinions expressed are the opinions =
= only of myself and may or may not reflect the opinions of anybody =
= else with whom I may or may not have discussed the issues at hand. =
========================================================================

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Received on Fri Mar 25 20:02:01 2005